Sedimentation tank having rotatable sediment conveying structure



March 22, 1966 E. w. COOKNEY ETAL 3, SEDIMENTATION TANK HAVING ROTATABLE SEDIMENT CONVEYING STRUCTURE Original Filed June 22, 1962 5 Sheets-Sheet 1 INVENTORS ERA/ESTk/COOKNEY PHUL PETE ass/v March 1966 E. w. COOKNEY ETAL 3,241,632

SEDIMENTATION TANK HAVING ROTATABLE SEDIMENT CONVEYING STRUCTURE Original Filed June 22, 1962 5 Sheets-Sheet 2 March 22, 1966 E. w. COOKNEY ETAL 3,241,682

SEDIMENTATION TANK HAVING ROTATABLE SEDIMENT CONVEYING STRUCTURE Original Filed June 22, 1962 5 Sheets-Sheet 5 Fig. 5.

INVENTORS: E/PNEil'g/COOKNEY PHUL 7'EIQ8E/V United States Patent "ice Continuation of application Ser. No. 204,463, June 22, 1962. This application Jan. 22, 1965, Ser. No. 432,045 11 Claims. (Cl. 210-528) This invention is a continuation of our application Serial No. 204,463, filed June 22, 1962, and now abancloned.

This invention relates to improvements in drive means applicable advantageously for example to continuously operating sedimentation tanks of large diameter wherein a rake structure is rotatably supported upon a base portion of the tank or center pier, with drive mechanism for the rake structure mounted on the pier, so that the rake structure when rota-ted will move sediment or sludge continously over the tank bottom to an outlet zone while clarified liquid overflows from the tank.

The pier supported rake structure in this type of tank has a central cage construction surrounding the pier, provided with a main gear or bull gear at the top, the cage construction and bull gear being supported for rotation about a vertical axis on a horizontal supporting frame, which frame in turn is on the pier. The toothed portions of the bull gear operates in an annular trough formed by or provided on the supporting frame.

For example, one or more drive pinion units are provided to engage the bull gear in driving relationship therewith. The upper end of each pinion shaft is connected to an associated gear rotated by interbalanced torque transmitting means. An upper bearing for the pinion shaft is mounted in a gear casing between the pinion and the associated gear, the gear casing itself being mounted on the supporting frame. The lower end of the pinion shaft has a bearing located below the pinion and mounted in the bottom portion of the trough structure.

The invention improves the operation of the drive pinion units in rotating the main or bull gear of the raking structure. More particularly, the aim is to provide a simple yet rugged anti-friction bearing arrangement for the pinion shaft, capable of effectively absorbing radial as well as axial drive reaction forces while maintaining optimum driving contact between the bull gear and the pinions, together with simple and easily maintainable lubricating means, the object being to minimize construction costs, wear and tear, and maintenance, as well as power consumption required in the rotation of the bull gear and the raking structure.

The foregoing objects are attainable by the provision of a drive pinion unit for the bull gear wherein the bearings for the pinion shaft cooperate to resist radial forces as well as axial thrust in both directions, the upper bearing being located in a trough formed by the gear casing, while the lower bearing is located in the bottom of the pocket formed on the supporting frame. Each bearing may thus operate in its own pool of oil contained respectively in the upper trough and in the lower bearing pocket without the need of conventional oil seal rings.

Preferably, the bearings are cooperating conical roller bearings, with a detachable retainer member for the lower bearing connected to the bottom end of the pinion shaft.

According to one feature, a working tolerance or preload in the bearings is closely adjustable by the adjustment axially of the pinion shaft relative to the associated gear, thereby achieving optimum working engagement between the bull gear and the drive pinions, thus minimiz- Patented Mar. 22, 1966 ing wear and tear as well as power consumption required for the operation of the raking structure in the tank.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims, or of forms that are their functional as well as conjointly cooperative equivalents, are therefore intended to be embraced by those claims.

FIG. 1 is a semi-diagrammatic illustration of a sedimentation tank of the center pier type embodying the invention;

FIG. 1a is an enlarged fragmentary view of the sedimentation tank of FIG. 1, indicating the drive arrangement for the rake structure on the pier;

FIG. 2 is an enlarged top view of the drive arrangement taken on line 2-- of FIG. 1a, showing the invention embodied in a torque balanced duplex pinion drive; FIG. 3 is a side view of the drive arrangement taken on line 33 of FIG. 2;

FIG. 4 is a sectional view of the drive arrangement taken on line 4-4 of FIG. 2;

FIG. 5 is a further enlarged detail sectional view taken on line 5-5 of FIG. 2', showing one of the drive pinion units embodying the invention;

FIG. 6 is a diagrammatic top view of a torque balanced arrangement of a pair of drive pinion units.

In the example of a continuously operating sedimentation tank herein shown to embody the invention, a rake structure 10 (see FIGS. 1 and la) is supported for rotation upon a center pier 11 rising from the bottom 10a of the tank. The central vertical cage construction 12 of the rake structure has truss-shaped rake arms 13 carrying sediment engaging blades 14. Thus, when the rake structure is rotated upon the pier, the blades will convey sediment or sludge over the tank bottom into an annular sump 15 surrounding the foot end of the pier for withdrawal through an underflow discharge pipe 16. Feed slurry or suspension is supplied to the tank through a feed conduit 17 suspended from a stationary truss or bridge 18 connecting the tank wall 19 with the top end of the center pier. The feed slurry is thus delivered into an annular feedwell 20 surrounding the cage structure 12 while clarified liquid overflows into a peripheral l-aunder 21 for discharge through an outlet pipe therefrom not shown. The drive head or drive mechanism for the rake structure, embodying the invention is designated collectively by the letter H. The drive mechanism is mounted upon the center pier being in the form of a twin pinion drive arrangement as an example embodying the invention which will now be described in connection with FIGS. 2 to 6 illustrating the improved drive arrangement as well as the drive pinion unit itself in more detail.

The drive arrangement comprises an internally toothed bull gear 22 connected to the top end of the cage construction 12, the bull gear being rotatable upon a large annular thrust bearing having a diameter D (see FIG. 4) with anti-friction ball elements 23 carried by the peripheral portion of a supporting frame 24 mounted upon the top end of the pier. The present example of the drive arrangement comprises a pair of pinion drive units 25 and 26 arranged as shown in FIGS. 2, 3 and 4, and constructed as shown in the detail FIG. 5. These drive pinion elements comprise respective drive pinions 27 and 28 engaging the bull gear at diametrically opposed points of torque application as is indicated diagrammatically in FIG. 6.

In the pinion drive units, according to FIG. 5, the pinion is accommodate in a pocket 29 formed in the supporting frame. The pinion has a pinion shaft 30, the upper end portion of which is connected to a worm gear 31 as indicated by the key connections 32 and 33, which gear has a driving worm 34.

The worm drive elements 31 and 34 contained in a casing 35. The worm shaft 36 is suitably journaled in the casing to allow for a degree of longitudinal movement thereof in the worm shaft bearings. More particularly, the casing comprises a shallow upper portion 35a surrounding the worm gear and the worm, formed at the bottom with an annular trough 37 having an inner annular wall 38 surrounding the pinion shaft 30. An upper combination bearing 39 is located in the trough, capable of absorbing radial forces as well as axial thrust, effective between the casing and the gear and lubricated by the oil contained in the trough. More particularly, this upper combination bearing comprises a set of conical anti-friction rollers 40 having upwardly converging axes, cooperating with an inner raceway member 41 fitted over the inner wall 38 of the trough, and with an outer raceway member 42 fitted into the underside of the associated gear.

The casing further has a lower portion 35b extending downwardly from the trough 37, surrounding the pinion shaft, and having a flange connection 43 with the supporting frame.

The lower end portion 44 of the pinion shaft below the pinion rotates in a lower combination bearing 45 effective between the pinion shaft and the supporting frame at the bottom of the aforementioned pocket 29 of the frame. More particularly, this lower combination bearing comprises a set of conical anti-friction rollers 46 having upwardly converging axes, cooperating with an inner raceway member 47 fitted over the .pinion shaft, and with an outer raceway member 48 seated in the bottom portion of the pocket in the supporting frame. A retainer member 49 is detachably fastened to the bottom face of the pinion shaft as indicated by fastening bolts 50, for securing the inner raceway member in position. A closure plate 51 constituting the bottom of the pocket is detachable to provide access to the bearing retainer plate 49.

The Working tolerances or pre-load pressures in the bearings themselves, are closely maintainable by the manipulation of suitable adjustment means whereby the pinion shaft 30 is axially adjustable relative to the associated worm gear 31. Such adjustment means preferably comprise a pair of locknuts 52 and 53 engaging the upper threaded end portion of the pinion shaft extending upwardly beyond the gear. Accordingly, this axial adjustment is made by turning nut 52 resting against the hub portion of the associated gear 31 until a desired amount of bearing contact or pre-load pressure in the bearings is attained, whereupon the companion nut 53 is tightened and secured relative to nut 50.

Lubricating oil may be supplied into the upper portion 35a of the gear casing up to a level effective to lubricate both the worm drive and the upper combination bearing in the trough, with provision for excess oil supplied to this casing portion to overflow the inner annular wall of trough 37 into the lower bearing pocket containing the lower combination bearing Where the oil level is made sufficiently high to provide lubrication also for the large annular thrust bearing of diameter D.

The two drive worms 34 and 34a of the respective pinion drive units 25 and 26 (see FIG. 2) are coaxially interconnected by a coupling shaft member 54 as through a pair of coupling devices 55 and 56, driven by a motor 57 mounted on bracket 58 provided on the gear casing of pinion drive unit 25. The power transmission from the motor to the pinions is indicated by a sprocket chain drive means 59. Inasmuch as the two drive worms 34 and 34a have relatively oppositely directed pitch, and

are axially displaceable as a unit to a degree, their respective axial force reaction thrusts will be in balance with each other. This balance of the axial thrust forces insures that equal shares of drive torque from the motor will reach the two drive pinions, thereby applying a balanced drive torque to the bull gear and the raking structure.

From the foregoing it will be seen that the invention in combining the adjustable cooperating upper and lower bearing means with the lubricating arrangement above set forth, provides highly practical structural as well as operational and economical advantages, and also novel technical results, which may be added to the advantages of an interbalanced multi-pinion drive arrangement.

We claim:

1. In a continuously operating sedimentation tank, having a bottom, the improved sediment conveying apparatus which comprises a frame structure supported at the top of the tank, and providing a horizontal trough having a bottom opening formed With a downwardly facing annular shoulder;

a main gear member including a toothed rim portion;

means for mounting said main gear member for rotation on said frame structure with the toothed rim portion of said main gear member operating in said trough;

a pinion member located in said trough in driving engagement with said main gear, and having downwardly and upwardly extending shaft portions;

a lower combined radial and vertical thrust bearing surrounding the lower shaft portion of said pinion member and comprising an outer race seated on the shoulder in said bottom opening, and an inner race mounted on said lower shaft portion of the pinion member, with antifriction bearing elements effective between said races, and retainer means for said inner race detachably mounted upon the lower end of said pinion member, said lower bearing being arranged for transmitting vertical thrust from said retainer means upwardly to said shoulder;

a detachable cover member closing said opening from below;

a coaxial gear member mounted upon the upper shaft portion of said pinion member in torque transmitting relationship therewith although axially movable thereon to a limited degree;

a housing structure surrounding said coaxial gear member and mounted on said frame structure, and formed with an annular groove surrounding said upper shaft portion underneath said coaxial gear member;

drive means in driving engagement with said coaxial gear member;

an upper combined radial and axial thrust bearing surrounding the upper shaft portion of said pinion member and located in said annular groove, and comprising an inner race and an outer race with antifriction bearing elements effective between said races, one of said races being mounted on said coaxial gear member, the other of said races being mounted on an adjacent portion of said housing structure, said upper bearing being arranged for transmitting axial thrust from said coaxial gear member downwardly to the housing structure;

adjustable means located at the upper side of said coaxial gear in engagement with said upwardly extending shaft portion as well as with said coaxial gear for axially positioning and locking said pinion member and said coaxial gear member relative to one another for establishing and maintaining said upper and lower hearings in cooperative relationship with respect to one another, as well as to maintain optimum gear meshing relationship between the pinion and the associated main gear;

and a sediment engaging rake structure connected to said main gear member and extending concentrically downwardly thcrefrom and effective to convey sediment over the tank bottom when said main gear member is rotated by said pinion member and its associated coaxial gear member.

2. The apparatus according to claim 1, wherein said tank bottom provides a base portion having a vertical support structure rising therefrom wherein said frame structure is supported on said vertical support structure, and wherein said sediment engaging rake structure comprises a vertical cage portion connected to and extending downwardly from said main gear member and surrounding said vertical support structure, and rake arms extending from said cage portion.

3. The apparatus according to claim 1, wherein said housing structure comprises an upper section surrounding said coaxial gear member and a lower section surrounding said upper shaft portion of the pinion member and forming therewith an annular space, and wherein said annular groove has overflow means for oil to overflow down through said annular space into the trough of said frame structure.

4. The apparatus according to claim 1, wherein said adjustable means comprise an abutment member having thread connection with said upwardly extending shaft portion of the pinion member whereby said abutment member is axially adjustable thereon.

5. The apparatus according to claim 1, wherein said upper thrust bearing has the inner race mounted on the housing structure, and the outer race mounted on said coaxial gear member.

6. The apparatus according to claim 1, wherein said upper and lower bearings are in the form of conical roller bearings arranged with the axes of the rollers of each bearing converging towards the axis of said coaxial gear member.

7. In a continuously operating sedimentation tank having a bottom providing a base portion with a vertical support structure risin-g therefrom, the improved sediment conveying apparatus which comprises a frame structure supported on said vertical structure and secured against rotation about a vertical axis, said frame structure providing a peripheral horizontal annular trough having an inner annular wall, an outer annular wall, and an annular bottom which has an opening formed with a downwardly facing annular shoulder;

an internally toothed bull gear member concentric with said annular trough and comprising an inner annular toothed portion extending into said trough and a rim portion extending outwardly from said toothed portion and across said outer annular wall of the trough;

annular main thrust bearing means located adjacent the inside of said outer wall and substantially concentric with said trough, whereby said bull gear member is supported for rotation on said frame structure;

a pinion member located in said trough in driving engagement with said internally toothed bull gear, and having downwardly and upwardly extending shaft portions;

a lower combined radial and vertical thrust bearing surrounding the lower shaft portion of said pinion member and comprising an outer bearing race seated on the shoulder in said bottom opening, and an inner bearing race mounted on said lower shaft portion of the pinion member, antifriction elements interposed between said bearing races, and retainer means for said inner race detachably mounted upon the lower end of said pinion member, said lower bearing being arranged for transmitting vertical thrust from said retainer means upwardly to said shoulder;

a detachable cover member closing said opening from below;

a coaxial gear member mounted upon the upper shaft portion of said pinion member in torque transmitting relationship therewith although axially movable thereon;

a housing structure surrounding said coaxial gear member and supported on said frame structure, and formed with an annular groove surrounding said upper shaft portion underneath said coaxial gear member;

means for mounting said housing structure on said frame structure;

drive means in driving engagement with said coaxial gear member;

an upper combined radial and axial thrust bearing surrounding the upper shaft portion of said pinion member and located in said annular groove, and comprising an inner bearing race and an outer hearing race with antifriction bearing elements effective between said races, one of said races being mounted on said coaxial gear member, the other of said races being mounted on an adjacent portion of said housing structure, said upper bearing being arranged for transmitting axial thrust from said coaxial gear member downwardly to the housing structure;

adjustable means located at the upper side of said coaxial gear in engagement with said upwardly extending shaft portion and with said coaxial gear, for axially positioning and locking said pinion member and said coaxial gear member relative to one another for establishing and maintaining said upper and lower bearings in adjusted cooperative relationship with respect to one another, as well as to maintain optimum gear meshing relationship between the pinion and the associated bull gear;

and a sediment engaging rake structure surrounding said vertical support structure and connected to said rim portion of the bull gear member, so as to be eifective to convey sediment over the tank bottom when said bull gear member is rotated by said pinion member and its associated coaxial gear member.

8. The apparatus according to claim 7, wherein said housing structure has an upper section surrounding said coaxial gear member and mounted on said frame structure, and having a lower section surrounding said upper shaft portion of the pinion member and forming therewith an annular space, and wherein said annular groove has overflow means for oil to overflow down through said annular space into the trough of the frame structure.

9. The apparatus according to claim 7, wherein said adjustable means comprise an abutment member having thread connection with said upwardly extending shaft portion of the pinion member whereby said abutment is axially adjustable thereon.

10. The apparatus according to claim 7, wherein said upper thrust bearing has the inner race mounted on the housing member, and the outer race mounted on said coaxial gear member.

11. The apparatus according to claim 7, wherein said upper and lower bearings are in the form of conical roller bearings arranged with the axis of the rollers of each bearing converging towards the axis of said coaxial gear member.

References Cited by the Examiner UNITED STATES PATENTS 691,922 1/ 1902 Whitely et al 308-207 1,438,570 12/ 1922 Zimmerman 308207 1,890,685 12/1932 Johnson 74-425 X 2,122,287 6/1938 Kepper 210-428 X 2,292,690 8/ 1942 Hoge 74425 2,560,990 7/1951 Schmitter 74665 2,710,457 6/1955 Cirrito et al 74425 2,866,352 12/1958 Scott 2l0--528 X REUBEN FRIEDMAN, Primary Examiner. 

1. IN A CONTINUOUSLY OPERATING SEDIMENTATION TANK, HAVING A BOTTOM, THE IMPROVED SEDIMENT CONVEYING APPARATUS WHICH COMPRISES A FRAME STRUCTURE SUPPORTED AT THE TOP OF THE TANK, AND PROVIDING A HORIZONTAL TROUGH HAVING A BOTTOM OPENING FORMED WITH A DOWNWARDLY FACING ANNULAR SHOULDER; A MAIN GEAR MEMBER INCLUDING A TOOTHED RIM PORTION; MEANS FOR MOUNTING SAID MAIN GEAR MEMBER FOR ROTATION ON SAID FRAME STRUCTURE WITH THE TOOTHED RIM PORTION OF SAID MAIN GEAR MEMBER OPERATING IN SAID TROUGH; A PINION MEMBER LOCATED IN SAID TROUGH IN DRIVING ENGAGEMENT WITH SAID MAIN GEAR, AND HAVING DOWNWARDLY AND UPWARDLY EXTENDING SHAFT PORTIONS; A LOWER COMBINED RADIAL AND VERTICAL THRUST BEARING SURROUNDING THE LOWER SHAFT PORTION OF SAID PINION MEMBER AND COMPRISING AN OUTER RACE SEATED ON THE SHOULDER IN SAID BOTTOM OPENING, AND AN INNER RACE MOUNTED ON SAID LOWER SHAFT PORTION OF THE PINION MEMBER, WITH ANTIFRICTION BEARING ELEMENTS EFFECTIVE BETWEEN SAID RACES, AND RETAINER MEANS FOR SAID INNER RACE DETACHABLY MOUNTED UPON THE LOWER END OF SAID PINION MEMBER, SAID LOWER BEARING BEING ARRANGED FOR TRANSMITTING VERTICAL THRUST FROM SAID RETAINER MEANS UPWARDLY TO SAID SHOULDER; A DETACHABLE COVER MEMBER CLOSING SAID OPENING FROM BELOW; A COAXIAL GEAR MEMBER MOUNTED UPON THE UPPER SHAFT PORTION OF SAID PINION MEMBER IN TORQUE TRANSMITTING RELATIONSHIP THEREWITH ALTHOUGH AXIALLY MOVABLE THEREON TO A LIMITED DEGREE; A HOUSING STRUCTURE SURROUNDING SAID COAXIAL GEAR MEMBER AND MOUNTED ON SAID FRAME STRUCTURE, AND FORMED WITH AN ANNULAR GROOVE SURROUNDING SAID UPPER SHAFT PORTION UNDERNEATH SAID COAXIAL GEAR MEMBER; DRIVE MEANS IN DRIVING ENGAGEMENT WITH SAID COAXIAL GEAR MEMBER; AN UPPER COMBINED RADIAL AND AXIAL THRUST BEARING SURROUNDING THE UPPER SHAFT PORTION OF SAID PORTION MEMBER AND LOCATED IN SAID ANNULAR GROOVE, AND COMPRISING A INNER RACE AND AN OUTER RACE WITH ANTIFRICTION BEARING ELEMENTS EFFECTIVE BETWEEN SAID RACES, ONE OF SAID RACES BEING MOUNTED ON SAID COAXIAL GEAR MEMBER, THE OTHER OF SAID RACES BEING MOUNTED ON AN ADJACENT PORTION OF SAID HOUSING STRUCTURE, SAID UPPER BEARING BEING ARRANGED FOR TRANSMITTING AXIAL THRUST FROM SAID COAXIAL GEAR MEMBER DOWNWARDLY TO THE HOUSING STRUCTURE; ADJUSTABLE MEANS LOCATED AT THE UPPER SIDE OF SAID COAXIAL GEAR IN ENGAGEMENT WITH SAID UPWARDLY EXTENDING SHAFT PORTION AS WELL AS WITH SAID COAXIAL GEAR FOR AXIALLY POSITIONING AND LOCKING SAID PINION MEMBER AND SAID COAXIAL GEAR MEMBER RELATIVE TO ONE ANOTHER FOR ESTABLISHING AND MAINTAINING SAID UPPER AND LOWER BEARINGS IN COOPERATIVE RELATIONSHIP WITH RESPECT TO ONE ANOTHER, AS WELL AS TO MAINTAIN OPTIMUM GEAR MESHING RELATIONSHIP BETWEEN THE PINION AND THE ASSOCIATED MAIN GEAR; AND A SEDIMENT ENGAGING RAKE STRUCTURE CONNECTED TO SAID MAIN GEAR MEMBER AND EXTENDING CONCENTRICALLY DOWNWARDLY THEREFROM AND EFFECTIVE TO CONVEY SEDIMENT OVER THE TANK BOTTOM WHEN SAID MAIN GEAR MEMBER IS ROTATED BY SAID PINION MEMBER AND ITS ASSOCIATED COAXIAL GEAR MEMBER. 